JP7333239B2 - Composite material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composite material having low friction slidability.

Conventionally, it has been known that a sliding surface having a polymer brush layer exhibits a low coefficient of friction. For example, in Patent Document 1, a sliding member having, on a sliding surface, a Si-containing diamond-like carbon layer formed on a substrate and a polymer brush layer covalently fixed on the Si-containing diamond-like carbon layer is provided. disclosed. The technique of Patent Document 1 aims to obtain a low coefficient of friction under oil lubrication.

Also, it is known that a polymer brush layer composed of a plurality of polymer graft chains exhibits a low coefficient of friction. For example, in Patent Document 2, a polymer graft chain is formed by copolymerizing methyl methacrylate and a monomer copolymerizable therewith on a base material, and such a polymer graft chain is formed by N , N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMI- A polymer brush layer is disclosed which is swollen with PF ₆ ).

JP 2012-56165 A WO2017/171071

According to the techniques of Patent Documents 1 and 2, the friction coefficient can be reduced to some extent in the friction sliding under oil lubrication in the former, and in the latter in the swollen polymer brush layer. From this point of view, materials with excellent low-friction slidability are desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite material having low-friction slidability.

As a result of intensive research to achieve the above object, the present inventors have found that a plurality of polymer chains immobilized on a substrate are combined with a salt and a hydrogen bond donating compound whose melting point is maintained at 100° C. or lower. The inventors have found that the above object can be achieved by a composite material swollen with a mixture containing the compound, and have completed the present invention.

（上記一般式（１）、（２）中、Ｒ^１～Ｒ^８は、それぞれ独立して、炭素数１～１２のアルキル基、炭素数６～１２のアリール基、－（ＣＨ_２）_ｍ－ＯＲ^９（Ｒ^９は、炭素数１～４のアルキル基であり、ｍは１～４である。）で表される基、－（ＣＨ_２）_ｎ－ＯＨ（ｎは、１～４の整数）で表される基、－（ＣＨ_２）_ｐ－ＯＣ（＝Ｏ）Ｒ^１０（Ｒ^１０は、炭素数１～４のアルキル基であり、ｐは１～４である。）で表される基、または－（ＣＨ_２）_ｑ－Ｙ^１（Ｙ^１は、ハロゲン元素、ｑは１～４である。）で表される基を示し、Ｘ^－は、一価のアニオンである。）
〔８〕前記複数の高分子鎖が、基材上に共有結合で固定されたものである前記〔１〕～〔７〕のいずれかに記載の複合材料、
〔９〕前記複数の高分子鎖の分子量分布（Ｍｗ／Ｍｎ）が１．５以下である前記〔８〕に記載の複合材料、
〔１０〕前記基材表面の面積に対する、前記複数の高分子鎖の専有面積率が１０％以上である前記〔８〕または〔９〕に記載の複合材料、
〔１１〕前記基材上に形成された、前記複数の高分子鎖と、前記混合物とを含む層の厚みが５００ｎｍ以上である前記〔８〕～〔１０〕のいずれかに記載の複合材料、
〔１２〕前記複数の高分子鎖が、主鎖となる高分子鎖から分岐した高分子グラフト鎖である前記〔１〕～〔１１〕のいずれかに記載の複合材料、
〔１３〕前記複数の高分子鎖が、架橋構造を形成している前記〔１〕～〔１２〕のいずれかに記載の複合材料、
が提供される。 That is, according to the present invention,
[1] A composite material obtained by swelling a plurality of polymer chains immobilized on a substrate with a mixture containing a salt and a hydrogen bond donating compound, the melting point of which is maintained at 100°C or less,
[2] The composite material according to [1] above, wherein the mixture has a melting point lower than the melting point of the salt constituting the mixture and the melting point of the hydrogen bond donating compound constituting the mixture;
[3] The above-mentioned [1] or [2], wherein the mixture has a melting point maintained at 100° C. or lower due to eutectic melting point depression caused by mixing the salt and the hydrogen bond donating compound. the composite material described,
[4] The composite material according to any one of [1] to [3], wherein the mixture further comprises a third component exhibiting compatibility with the salt and the hydrogen bond donating compound;
[5] The mixture according to any one of [1] to [4] above, which contains a salt that is solid at normal temperature (25° C.) and a hydrogen bond donating compound that is solid at normal temperature (25° C.). composite materials,
[6] The above [1] to wherein the ratio of the salt and the hydrogen bond donating compound constituting the mixture is 1:0.5 to 1:12 in terms of the molar ratio of "salt:hydrogen bond donating compound" The composite material according to any one of [5],
[7] The composite material according to any one of [1] to [6], wherein the salt constituting the mixture is a compound represented by the following general formula (1) or (2):

(In general formulas (1) and (2) above, R ¹ to R ⁸ are each independently an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, —(CH ₂ ) _m — a group represented by OR ⁹ (R ⁹ is an alkyl group having 1 to 4 carbon atoms and m is 1 to 4), —(CH ₂ ) _n —OH (n is an integer of 1 to 4) ), and —(CH ₂ ) _p —OC(=O)R ¹⁰ (R ¹⁰ is an alkyl group having 1 to 4 carbon atoms, and p is 1 to 4.) group, or a group represented by -(CH ₂ ) _q -Y ¹ (Y ¹ is a halogen element, q is 1 to 4), and X ^- is a monovalent anion.)
[8] The composite material according to any one of [1] to [7], wherein the plurality of polymer chains are covalently fixed on a substrate;
[9] The composite material according to [8] above, wherein the molecular weight distribution (Mw/Mn) of the plurality of polymer chains is 1.5 or less;
[10] The composite material according to [8] or [9] above, wherein the exclusive area ratio of the plurality of polymer chains to the surface area of the base material is 10% or more;
[11] The composite material according to any one of [8] to [10], wherein the layer containing the plurality of polymer chains and the mixture formed on the substrate has a thickness of 500 nm or more;
[12] The composite material according to any one of [1] to [11], wherein the plurality of polymer chains are polymer graft chains branched from a polymer chain serving as a main chain;
[13] The composite material according to any one of [1] to [12], wherein the plurality of polymer chains form a crosslinked structure,
is provided.

ADVANTAGE OF THE INVENTION According to this invention, the composite material which has low friction slidability can be provided.

FIG. 1 is a schematic diagram showing an example of the composite material according to the first embodiment of the present invention. FIG. 2 is a schematic diagram showing the structure of a branched graft chain-containing polymer according to the third embodiment of the present invention. FIG. 3 is a graph showing the results of friction force measurement of Examples 1 to 3, 5 and 6 and Comparative Examples 1 and 2. FIG. FIG. 4 is a graph showing the results of frictional force measurement of Example 4. FIG.

The composite material of the present invention is obtained by swelling a plurality of polymer chains immobilized on a substrate with a mixture containing a salt and a hydrogen bond donating compound, the melting point of which is maintained at 100° C. or lower.

The composite material of the present invention can function as a tribology system material (SRT material) having softness and resilience by having the above configuration.

<First embodiment>
First, a first embodiment of the present invention will be described.
FIG. 1 is a schematic diagram showing a composite material according to a first embodiment of the invention. As shown in FIG. 1, the composite material according to the first embodiment of the present invention comprises a substrate 10 and a polymer brush layer 20 formed on the substrate 10. As shown in FIG.

The base material 10 is not particularly limited, and can be appropriately selected from organic materials, inorganic materials, metal materials, and the like.

For example, materials for forming the base material 10 include:
Polyurethane materials, polyvinyl chloride materials, polystyrene materials, polyolefin materials, PMMA, PET, cellulose acetate, silica, inorganic glass, paper, plastic laminate films, ceramics (alumina ceramics, bioceramics, zirconia-alumina composite ceramics, etc.) composite ceramics, etc.);
Metals (aluminum, zinc, copper, titanium, etc.), metal-deposited paper, silicon, silicon oxide, silicon nitride, polycrystalline silicon, and composites thereof;
Polyolefin (polyethylene, polypropylene, polyisobutylene, ethylene alpha olefin copolymer, etc.), silicone polymer, acrylic polymer (polyacrylonitrile, polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, etc.), fluoropolymer (polytetrafluoroethylene , chlorotrifluoroethylene, fluorinated ethylene-propylene, polyvinyl fluoride, etc.), vinyl polymers (polyvinyl chloride, polyvinyl methyl ether, polystyrene, polyvinyl acetate, polyvinyl ketone, etc.), vinyl monomer-containing copolymers (ABS, etc.) , Natural and synthetic rubber (latex rubber, butadiene-styrene copolymer, polyisoprene, polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene polymer, polyisobutylene rubber, ethylene-propylenediene copolymer, polyisobutylene-isoprene, etc.) ), polyurethane (polyether urethane, polyester urethane, polycarbonate urethane, polysiloxane urethane, etc.), polyamide (nylon 6, nylon 66, nylon 10, nylon 11, etc.), polyester, epoxy polymer, cellulose, modified cellulose, and these hydrophobic organic materials such as copolymers;
Hydrophilic acrylic polymers (polyacrylamide, poly-2-hydroxyethyl acrylate, poly-N,N-dimethylacrylamide, polyacrylic acid, polymethacrylic acid, etc.), hydrophilic vinyl polymers (poly-N-vinylpyrrolidone, polyvinyl pyridine, etc.), polymaleic acid, poly-2-hydroxyethyl fumarate, maleic anhydride, polyvinyl alcohol, and hydrophilic organic materials such as copolymers thereof;

The shape of the base material 10 is not particularly limited, and examples thereof include tubes, sheets, fibers, strips, films, plates, foils, membranes, pellets, powders, molded products (extrusion molded products, cast molded products, etc.). is mentioned.

For example, when the composite material according to the first embodiment is used for seal applications, the base material 10 is preferably rubber (for oil seal applications) or inorganic oxide (for mechanical seal applications).
When the composite material according to the first embodiment is used as a bearing, the substrate 10 is preferably metal (SUS, SUJ2, carbon steel, etc.) or resin (polyethylene, etc.).
When the composite material according to the first embodiment is used as a guide (guide mechanism), the base material 10 is preferably metal (SUS, SUJ2, carbon steel, etc.) or resin (polyphenylene sulfide, polytetrafluoroethylene, etc.). .
When the composite material according to the first embodiment is used for a sliding member, the base material 10 includes cast iron, steel, iron such as stainless steel, iron alloys, non-ferrous metals and non-ferrous alloys such as aluminum and copper, and silicon. Wafers, glass, non-metals such as quartz, etc. are preferred.

The polymer brush layer 20 is a mixture containing a salt and a hydrogen bond donating compound, in which a plurality of polymer chains covalently fixed on the substrate 10 as a substrate has a melting point maintained at 100° C. or less. It is a layer formed by being swollen. In addition, in the first embodiment, the plurality of polymer chains may be a plurality of polymer graft chains.

According to the first embodiment, a salt and a hydrogen bond donating compound having a melting point maintained at 100° C. or lower are used as swelling agents for swelling the plurality of polymer chains constituting the polymer brush layer 20 . (hereinafter referred to as a “salt-hydrogen bond donor mixture” as appropriate) is used, which can reduce the friction coefficient of the polymer brush layer 20 and provide excellent low-friction slidability. Since it is excellent in low-friction slidability, it can be suitably used as various sealing materials, or as sliding members or sliding materials used for sliding parts of various devices. be.

The salt-hydrogen bond donor mixture used in the first embodiment is not particularly limited as long as it contains a salt and a hydrogen bond donor compound and has a melting point maintained at 100° C. or lower. , a mixture of a salt that is solid at room temperature (25° C.) and a hydrogen bond donating compound that is solid or liquid at room temperature (25° C.).

The salt that constitutes the salt-hydrogen bond donor mixture and is solid at room temperature (25° C.) is not particularly limited, but organic salts and inorganic salts can be used without limitation. Preferable examples include an ammonium salt represented by (1) and a phosphonium salt represented by the following general formula (2). The salts that are solid at room temperature (25° C.) may be used singly or in combination of two or more.

In general formula (1) above, R ¹ to R ⁴ each independently represent an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, —(CH ₂ ) _m —OR ⁹ (R ⁹ is an alkyl group having 1 to 4 carbon atoms, and m is 1 to 4.), a group represented by —(CH ₂ ) _n —OH (n is an integer of 1 to 4) a group represented by —(CH ₂ ) _p —OC(=O)R ¹⁰ (R ¹⁰ is an alkyl group having 1 to 4 carbon atoms and p is 1 to 4), or —( CH ₂ ) _q -Y ¹ (Y ¹ is a halogen element, q is 1 to 4), and X ^- is a monovalent anion.

The alkyl group having 1 to 12 carbon atoms may be linear, branched or cyclic, and may be methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl or s-butyl. group, isobutyl group, t-butyl group, cyclobutyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n- dodecyl group, cyclopentyl group, cyclohexyl group and the like. These may have a substituent.

Examples of the aryl group having 6 to 12 carbon atoms include phenyl group, benzyl group, tolyl group, xylyl group, naphthyl group and biphenyl group. These may have a substituent.

The group represented by —(CH ₂ ) _m —OR ⁹ (R ⁹ is an alkyl group having 1 to 4 carbon atoms and m is 1 to 4) includes a methoxymethyl group, an ethoxymethyl group, propoxymethyl group, butoxymethyl group, methoxyethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, methoxypropyl group, ethoxypropyl group, methoxybutyl group, ethoxybutyl group and the like, among which methoxyethyl groups, ethoxyethyl groups are preferred.

The group represented by —(CH ₂ ) _n —OH (n is an integer of 1 to 4) includes a hydroxymethyl group, a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 3-hydroxypropyl group, a 2- A hydroxybutyl group, a 3-hydroxybutyl group, a 4-hydroxybutyl group and the like can be mentioned, and among these, a 2-hydroxyethyl group is preferred.

The group represented by —(CH ₂ ) _p —OC(=O)R ¹⁰ (R ¹⁰ is an alkyl group having 1 to 4 carbon atoms and p is 1 to 4) includes a methyl acetate group (--CH ₂ --OC(=O)CH ₃ ), ethyl acetate group (--C ₂ H ₄ --OC(=O)CH ₃ ), propyl acetate group (--C ₃ H ₆ --OC(=O)CH ₃ ), butyl acetate group ( _{-C4H8 -} OC(=O _{)CH3), methyl propionate group (-CH2-OC(=O)C2H5 ) , ethyl} propionate group ( _{-C2H 4} -OC(=O) _C2H5 ), propyl propionate group ( _{-C3H6 -} OC ₍ =O) _{C2H5 )} , butyl propionate group ( _{-C4H8 -} OC(=O )C ₂ H ₅ ) and the like, and among these, an ethyl acetate group (--C ₂ H ₄ --OC(=O)CH ₃ ) is preferred.

The group represented by —(CH ₂ ) _q —Y ¹ (Y ¹ is a halogen element and q is 1 to 4) includes a methyl fluoride group, a methyl chloride group, a methyl bromide group, an iodide group, methyl group, 2-ethyl fluoride group, 2-ethyl chloride group, 2-ethyl bromide group, 2-ethyl iodide group, 3-propyl fluoride group, 3-propyl chloride group, 3-propyl bromide group, A 3-iodide propyl group and the like can be mentioned, and among these, a 2-ethyl chloride group is preferable.

In addition, X ⁻ represents a monovalent anion, and examples of the monovalent anion include, but are not limited to, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , and CF _{3 .} BF ₃ ⁻ , C ₂ F ₅ BF ₃ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , AlCl ₄ ⁻ , HSO ₄ ⁻ , ClO ₄ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO ₂ ^- , (CF ₃ SO ₂ ) ₂ N ^- and the like. Among these, halogen anions such as Cl ⁻ , Br ⁻ and I ⁻ are preferred, and Cl ⁻ is particularly preferred.

In the general formula (2), R ⁵ to R ⁸ each independently represent an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, —(CH ₂ ) _m —OR ⁹ (R ⁹ is an alkyl group having 1 to 4 carbon atoms, and m is 1 to 4.), a group represented by —(CH ₂ ) _n —OH (n is an integer of 1 to 4) a group represented by —(CH ₂ ) _p —OC(=O)R ¹⁰ (R ¹⁰ is an alkyl group having 1 to 4 carbon atoms and p is 1 to 4), or —( CH ₂ ) _q —Y ¹ (Y ¹ is a halogen element, q is 1 to 4), and specific examples thereof include R ¹ to R ⁴ are exemplified. X ^{1 −} represents a monovalent anion, and specific examples thereof include those exemplified in the above general formula (1).

In the first embodiment, from the viewpoint that the friction coefficient of the polymer brush layer 20 can be further reduced and the low-friction slidability can be improved, the ammonium salt represented by the general formula (1) or Among the phosphonium salts represented by the above general formula (2), the ammonium salts represented by the following general formula (3) are preferred.

In general formula (3) above, R ¹ to R ³ , X ⁻ , and n are the same as in general formula (1) above, and R ¹ to R ³ are each independently a methyl group or an ethyl group. is preferred, and it is particularly preferred that all of R ¹ to R ³ are methyl groups. Also, n is preferably 1 or 2, particularly preferably 2, and X ⁻ is preferably a halogen anion, particularly preferably Cl ^{2 −} .

Further, the salt that is solid at room temperature (25° C.) is an ammonium salt represented by the above general formula (1), and each of R ¹ to R ⁴ is an alkyl group having 1 to 12 carbon atoms. is also suitable, more preferably R ¹ to R ⁴ are all alkyl groups having 1 to 6 carbon atoms, and particularly R ¹ to R ⁴ are all the same alkyl group preferable. In this case, R ¹ to R ⁴ are methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, cyclobutyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, among others, n-butyl group, s-butyl group, isobutyl group, t-butyl group, cyclobutyl group An alkyl group having 4 carbon atoms such as a group is preferred, and an n-butyl group is more preferred.

Furthermore, when the phosphonium salt represented by the general formula (2) is used as a salt that is solid at room temperature (25° C.), R ⁵ to R ⁸ are all alkyl having 1 to 12 carbon atoms groups, more preferably all of R ⁵ to R ⁸ are alkyl groups having 1 to 6 carbon atoms, and particularly preferably all of R ¹ to R ⁴ are the same alkyl group. . In this case, R ¹ to R ⁴ are methyl group, ethyl group, n-propyl group, isopropyl group, cyclopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, cyclobutyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, among others, n-butyl group, s-butyl group, isobutyl group, t-butyl group, cyclobutyl group An alkyl group having 4 carbon atoms such as a group is preferred, and an n-butyl group is more preferred.

Inorganic salts may be used as salts that are solid at room temperature (25° C.), and examples of inorganic salts include metal halide salts. Examples of metal halide salts include terbium chloride, zinc chloride, zinc bromide, zirconium chloride, iron chloride, tin chloride, copper chloride, and magnesium chloride.

Further, the hydrogen bond donating compound constituting the salt-hydrogen bond donor mixture may be any compound that exhibits hydrogen bond donating properties, and is solid at room temperature (25° C.) or liquid at room temperature (25° C.). but not particularly limited, for example, chain aliphatic polyhydric alcohols such as ethylene glycol, glycerin, hexanediol, 1,4-butanediol, triethylene glycol; aromatics such as resorcinol Group polyhydric alcohols; sugars such as glucose, sucrose and xylose; sugar alcohols such as xylitol and D-sorbitol; isosorbide compounds such as D-isosorbide; urea, thiourea, 1-methylurea, 1,3-dimethylurea, Urea compounds such as 1,1-dimethylurea; Amide compounds such as acetamide, benzamide and 2,2,2-trifluoroacetamide; Imidazole compounds such as imidazole; Formic acid, acetic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid , octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, eicosanoic acid, docosanoic acid, tetilacosanoic acid, hexacosanoic acid, octacosanoic acid, triacontanoic acid, etc. Monocarboxylic acids; hydroxyl group-containing aliphatic monocarboxylic acids such as lactic acid, tartaric acid, ascorbic acid and citric acid; aromatic monocarboxylic acids such as benzoic acid, cinnamic acid, trans-cinnamic acid, phenylacetic acid and 3-phenylpropionic acid carboxylic acids; hydroxyl group-containing aromatic monocarboxylic acids such as 4-hydroxybenzoic acid, caffeic acid, p-coumaric acid and gallic acid;

From the viewpoint that the coefficient of friction of the polymer brush layer 20 can be further reduced and the low-friction slidability can be improved, the hydrogen bond donating compound is preferably an aliphatic polyhydric alcohol or a urea compound. Glycol, glycerin or urea are preferred. In addition, a hydrogen bond donating compound may be used individually by 1 type, and may be used in combination of 2 or more types.

In the first embodiment, as the salt-hydrogen bond donor mixture, a salt such as a salt that is solid at room temperature (25° C.) and a hydrogen bond donor compound that is solid or liquid at room temperature (25° C.) are used. , A combination of a salt that is solid at room temperature (25 ° C.) and a hydrogen bond donating compound that is solid at room temperature (25 ° C.), Any combination of a salt that is solid at (25° C.) and a hydrogen bond donating compound that is liquid at room temperature (25° C.) may be used.

In the first embodiment, from the viewpoint that the coefficient of friction of the polymer brush layer 20 can be further reduced and the low-friction slidability can be made more excellent, either of the following (1) or (2) Aspects are preferred.

Specifically, as an aspect of (1), the melting point (T _{m_mixture} ) of the salt-hydrogen bond donor mixture is the melting point (T _{m_salt} ) of the salt itself, which constitutes the salt-hydrogen bond donor mixture, and the hydrogen bond donor (i.e., T _{m_mixture} < T _{m_salt} and T _{m_mixture} < T _{m_donor} ) so that the melting point _is maintained at 100° C. or lower is preferably That is, for example, when a salt having a melting point of 200° C. and a hydrogen bond donor compound having a melting point of 70° C. are used, the salt-hydrogen bond donor mixture obtained by mixing them has a melting point of 70° C. It is preferably such that it is less than In this case, when two or more kinds are used in combination as salts and/or hydrogen bond donor compounds, than the melting points of all salts and all hydrogen bond donor compounds that make up the salt-hydrogen bond donor mixture, Preferably, the salt-hydrogen bond donor mixture has a lower melting point.

Alternatively, as an aspect of (2), the salt-hydrogen bond donor mixture has a melting point of 100 ° C. due to eutectic melting point depression (eutectic melting point depression) due to mixing of the salt and the hydrogen bond donor compound. It is preferable that the following is maintained. By mixing such a salt and a hydrogen bond donating compound, eutectic melting point depression occurs, and as a mixture in which the melting point is maintained at 100° C. or less, for example, a deep eutectic solvent and may be called. In the aspect (2), any combination that causes eutectic melting point depression by mixing the salt and the hydrogen bond donating compound may be used. Similarly, the melting point of the salt-hydrogen bond donor mixture (T _{m_mixture} ) is the melting point of the salt itself (T _{m_salt} ) and the melting point of the hydrogen bond donor compound itself (T _{m_donor} ) (T _{m_mixture} < T _{m_salt} and T _{m_mixture} < T _{m_donor} ).

The method for preparing the salt-hydrogen bond donor mixture is not particularly limited, but if it is a mixture of solids at room temperature, weigh them in a mortar and mix while crushing the lumps, then put them in a glass container together with a stirrer. , a method of mixing while applying heat at about 70 ° C., or depending on the type of solid, eutectic occurs only by mixing in a mortar or the like (that is, without applying heat at about 70 ° C.), and the salt-hydrogen bond donor A method of forming a mixture (for example, a method of forming at room temperature by mixing) and the like can be mentioned. On the other hand, as a method of dissolving using a solvent, a salt and a hydrogen bond donating compound are mixed using a volatile solvent such as methanol, ethanol, acetone, or water, and the solvent is removed to prepare. There is a method (preferably, a method of causing eutectic in the process of mixing with a solvent or removing the solvent), which may be selected as appropriate. In particular, the salt-hydrogen bond donor mixture used in the first embodiment can be easily produced by mixing in a volatile solvent, and is therefore inexpensive, and can be used at room temperature (25 ℃) and a hydrogen bond donating compound that is solid or liquid at normal temperature (25 ℃), generally have low volatility and low ignitability is.

The ratio of the salt and the hydrogen bond donating compound in the salt-hydrogen bond donor mixture is preferably 1:0.5 to 1:12 in terms of the molar ratio of "salt:hydrogen bond donating compound", More preferably 1:0.5 to 1:8, still more preferably 1:0.5 to 1:3.5, and particularly preferably 1:1.5 to 1:3.5. By setting the ratio of the salt to the hydrogen bond donating compound within the above range, the melting point of the salt-hydrogen bond donor mixture can be effectively lowered, whereby when applied to the polymer brush layer 20, the polymer The friction coefficient of the brush layer 20 can be further reduced, and the low-friction slidability can be made more excellent.

The salt-hydrogen bond donor mixture may have a melting point maintained at 100° C. or lower, but preferably has a melting point of 70° C. or lower, more preferably 40° C. or lower. Those having a melting point of normal temperature (25° C.) or lower are more preferable. That is, it is preferable that it is a liquid at room temperature, and more preferable that it has a melting point of 15° C. or lower, and particularly preferable that it has a melting point of 0° C. or lower. Moreover, in the case where it is liquid at room temperature, it may not have a melting point.

Furthermore, in the first embodiment, the salt-hydrogen bond donor mixture may be a solution in which components other than the above-described salt and hydrogen bond donor compound (hereinafter referred to as "third component") are dissolved. . Such a third component is not particularly limited as long as it is compatible with the above-described salt and hydrogen bond donating compound. It is preferred that they are capable of dissolving, thereby forming a homogeneously dissolved mixture. By forming a uniformly dissolved mixture, it can be applied uniformly to the plurality of polymer chains constituting the polymer brush layer 20, and as a result, a uniform swollen structure can be obtained. In addition, when such other components are contained, as long as the solubility can be ensured, a mode in which adsorbed water is present may be employed.

Such third components include water, alcohols [e.g., alkanols (methanol, ethanol, 1-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, etc.), alkanediols (ethylene glycol, propylene glycol, etc.), alkanetriol (glycerin, etc.), low molecular weight polyalkylene glycol (diethylene glycol, triethylene glycol, etc.), ketones (acetone, dialkyl ketones, etc.), ethers, ionic liquids, etc. . These components may be used alone or in combination of two or more, and components capable of adjusting the viscosity of the salt and the hydrogen bond donating compound are preferred.

When the other components are contained in the salt-hydrogen bond donor mixture, the content ratio of the other components is not particularly limited, but the total salt-hydrogen bond donor mixture (that is, the salt, the hydrogen bond donor compound, and the It is preferably 0.1 to 75% by weight, more preferably 1 to 50% by weight, when the total of other components) is 100% by weight.

Then, in the first embodiment, the polymer brush layer 20 shown in FIG. The introduced polymer chains can be formed by swelling with the salt-hydrogen bond donor mixtures described above. In this case, the salt-hydrogen bond donor mixtures described above may be used singly or in combination of two or more. Further, as a swelling agent, in addition to the salt-hydrogen bond donor mixture described above, other media may be used in combination, and such other media include ionic liquids, organic solvents, lubricating oils, and the like. be done. The amount of the other medium to be used may be set as appropriate within a range that does not impair the effects of the present invention.

In the surface-initiated living radical polymerization method, a polymer chain is formed by introducing a polymerization initiating group onto the surface of the substrate 10, which serves as the starting point of the polymer chain, and performing living radical polymerization using the polymerization initiating group as the starting point. For example, the methods described in JP-A-2009-59659 and JP-A-2010-218984 can be applied.

The polymer for forming the polymer chain may be either a hydrophobic polymer or a hydrophilic polymer, and the hydrophilic polymer may be prepared using a hydrophilic monomer. It may be prepared by preparing a polymer using monomers and then introducing a hydrophilic group into this polymer. Further, the polymer chain may be a homopolymer of one type of monomer or a copolymer of two or more types of monomers. Any of gradient copolymerization and the like may be used.

The monomer used for forming the polymer chain is not particularly limited, but a monomer having at least one addition-polymerizable double bond is preferred. Preferred examples of the monofunctional monomer having one addition-polymerizable double bond include (meth)acrylic acid-based monomers and styrene-based monomers.

Examples of monomers used to form the polymer chain include (meth)acrylic acid-based monomers, styrene-based monomers, monofunctional monomers having one addition-polymerizable double bond, hydrophobic monomers, hydrophilic monomers, Examples thereof include monomers having a carboxyl group or a group that can be easily converted to a carboxyl group in the side chain.

Specific examples of (meth)acrylic acid-based monomers include:
(meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate;
heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate;
2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, stearyl (meth)acrylate , glycidyl (meth)acrylate, 3-ethyl-3-(meth)acryloyloxymethyloxetane;
2-(meth)acryloyloxyethyl isocyanate, (meth)acrylate-2-aminoethyl, 2-(2-bromopropionyloxy)ethyl (meth)acrylate, 2-(2-bromoisobutyryloxy)ethyl (meth) acrylate;
1-(meth)acryloxy-2-phenyl-2-(2,2,6,6-tetramethyl-1-piperidinyloxy)ethane, 1-(4-((4-(meth)acryloxy)ethoxyethyl) ) phenylethoxy)piperidine, γ-(methacryloyloxypropyl)trimethoxysilane;
3-(3,5,7,9,11,13,15-heptaethylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yl) Propyl (meth)acrylate, 3-(3,5,7,9,11,13,15-heptaisobutyl-pentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octa Siloxane-1-yl)propyl (meth)acrylate, 3-(3,5,7,9,11,13,15-heptaisooctylpentacyclo[9.5.1.1 ^{3,9.1 5,15} .1 ^7,13 ]octasiloxane-1-yl)propyl (meth)acrylate;
3-(3,5,7,9,11,13,15-heptacyclopentylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yl) Propyl (meth)acrylate, 3-(3,5,7,9,11,13,15-heptaphenylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octa Siloxane-1-yl)propyl (meth)acrylate, 3-[(3,5,7,9,11,13,15-heptaethylpentacyclo[9.5.1.1 ^{3,9.1 5,15} .1 ^7,13 ]octasiloxane-1-yloxy)dimethylsilyl]propyl (meth)acrylate;
3-[(3,5,7,9,11,13,15-heptaisobutylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yloxy ) dimethylsilyl]propyl (meth)acrylate, 3-[(3,5,7,9,11,13,15-heptaisooctylpentacyclo[9.5.1.1 ^{3,9.1 5,15} . 1 ^7,13 ]octasiloxane-1-yloxy)dimethylsilyl]propyl (meth)acrylate;
3-[(3,5,7,9,11,13,15-heptacyclopentylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yloxy ) dimethylsilyl]propyl (meth)acrylate, 3-[(3,5,7,9,11,13,15-heptaphenylpentacyclo[9.5.1.1 ^{3,9.1 5,15.1 7,13} ]octasiloxane-1-yloxy)dimethylsilyl]propyl (meth)acrylate;
(Meth)acrylic acid ethylene oxide adduct, trifluoromethylmethyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl-2-perfluorobutyl ethyl (meth)acrylate, 2-perfluoroethyl (meth)acrylate, trifluoromethyl (meth)acrylate, diperfluoromethylmethyl (meth)acrylate;
2-perfluoromethyl-2-perfluoroethylethyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate; .

Specific examples of styrene-based monomers include
Styrene, vinyltoluene, α-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, m-chloromethylstyrene, o-aminostyrene, p-styrenechlorosulfonic acid, styrenesulfonic acid and its salts, vinylphenylmethyldithio carbamate, 2-(2-bromopropionyloxy)styrene, 2-(2-bromoisobutyryloxy)styrene;
1-(2-((4-vinylphenyl)methoxy)-1-phenylethoxy)-2,2,6,6-tetramethylpiperidine, 1-(4-vinylphenyl)-3,5,7,9, 11,13,15-heptaethylpentacyclo[9.5.1.1 ^3,9 . ^15,15 . 1 ^7,13 ]octasiloxane, 1-(4-vinylphenyl)-3,5,7,9,11,13,15-heptaisobutylpentacyclo[9.5.1.1 ^3,9 . ^15,15 . 1 ^7,13 ]octasiloxane;
1-(4-vinylphenyl)-3,5,7,9,11,13,15-heptaisooctylpentacyclo[9.5.1.1 ^3,9 . ^15,15 . 1 ^7,13 ]octasiloxane, 1-(4-vinylphenyl)-3,5,7,9,11,13,15-heptacyclopentylpentacyclo[9.5.1.1 ^3,9 . ^15,15 . 1 ^7,13 ]octasiloxane, 1-(4-vinylphenyl)-3,5,7,9,11,13,15-heptaphenylpentacyclo[9.5.1.1 ^3,9 . ^15,15 . 1 ^7,13 ]octasiloxane;
3-(3,5,7,9,11,13,15-heptaethylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yl) Ethylstyrene, 3-(3,5,7,9,11,13,15-heptaisobutylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1 -yl)ethylstyrene, 3-(3,5,7,9,11,13,15-heptaisooctylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ] octasiloxane-1-yl)ethylstyrene;
3-(3,5,7,9,11,13,15-heptacyclopentylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yl) Ethylstyrene, 3-(3,5,7,9,11,13,15-heptaphenylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1 -yl)ethylstyrene, 3-(3,5,7,9,11,13,15-heptaethylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octa siloxane-1-yloxy)dimethylsilyl)ethylstyrene;
3-(3,5,7,9,11,13,15-heptaisobutylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yloxy) dimethylsilyl)ethylstyrene, 3-(3,5,7,9,11,13,15-heptaisooctylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ] octasiloxane-1-yloxy)dimethylsilyl)ethylstyrene;
3-((3,5,7,9,11,13,15-heptacyclopentylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ]octasiloxane-1-yloxy )dimethylsilyl)ethylstyrene, 3-((3,5,7,9,11,13,15-heptaphenylpentacyclo[9.5.1.1 ^3,9 .1 ^5,15 .1 ^7,13 ] octasiloxane-1-yloxy)dimethylsilyl)ethylstyrene; and the like.

Specific examples of monofunctional monomers having one addition-polymerizable double bond include:
Fluorine-containing vinyl monomers (perfluoroethylene, perfluoropropylene, vinylidene fluoride, etc.), silicon-containing vinyl monomers (vinyltrimethoxysilane, vinyltriethoxysilane, etc.), maleic anhydride, maleic acid, maleic acid monoalkyl esters and dialkyls esters, fumaric acid, mono- and dialkyl esters of fumaric acid;
Maleimide-based monomers (maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, stearylmaleimide, phenylmaleimide, cyclohexylmaleimide, etc.);
Nitrile group-containing monomers (acrylonitrile, methacrylonitrile, etc.), amide group-containing monomers (acrylamide, methacrylamide, etc.), vinyl ester monomers (vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, vinyl cinnamate, etc.) ;
Olefins (ethylene, propylene, etc.), conjugated diene monomers (butadiene, isoprene, etc.), vinyl halides (vinyl chloride, etc.), vinylidene halides (vinylidene chloride, etc.), allyl halides (allyl chloride, etc.);
allyl alcohol, vinylpyrrolidone, vinylpyridine, N-vinylcarbazole, methylvinylketone, vinylisocyanate;
Further, the monofunctional monomer having one addition polymerizable double bond includes one polymerizable double bond in one molecule, and the main chain is styrene, (meth)acrylic acid ester, Macromonomers and the like derived from siloxanes and the like can also be used.

Specific examples of hydrophobic monomers include
Acrylic acid esters (alkyl esters of acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, hexafluoroisopropyl acrylate; aryl acrylates such as phenyl acrylate; aryl alkyl acrylates such as benzyl acrylate; methoxymethyl acrylate, etc. alkoxyalkyl acrylate, etc.);
Methacrylic acid esters (alkyl esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, hexafluoroisopropyl methacrylate; aryl methacrylates such as phenyl methacrylate; arylalkyl methacrylates such as benzyl methacrylate; methoxymethyl methacrylate, etc. alkoxyalkyl methacrylate, etc.);
fumaric acid ester (dimethyl fumarate, diethyl fumarate, alkyl ester of fumaric acid such as diallyl fumarate, etc.), maleic acid ester (alkyl ester of maleic acid such as dimethyl maleate, diethyl maleate, diallyl maleate, etc.);
Itaconic acid esters (such as alkyl esters of itaconic acid), crotonic acid esters (such as alkyl esters of crotonic acid), methyl vinyl ether, ethoxyethyl vinyl ether, vinyl acetate, vinyl propionate, vinyl benzoate, styrene;
Alkyl styrene, vinyl chloride, vinyl methyl ketone, vinyl stearate, vinyl alkyl ether;

Specific examples of hydrophilic monomers include
hydroxy-substituted alkyl acrylates (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, polyethoxyethyl acrylate, polyethoxypropyl acrylate, etc.);
hydroxy-substituted alkyl methacrylates (2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, 2,3-dihydroxypropyl methacrylate, polyethoxyethyl methacrylate, polyethoxypropyl methacrylate, etc.);
acrylamide, N-alkylacrylamide (N-methylacrylamide, N,N-dimethylacrylamide, etc.), N-alkylmethacrylamide (N-methylmethacrylamide, etc.);
polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, alkoxypolyethyleneglycol acrylate, alkoxypolyethyleneglycol methacrylate, phenoxypolyethyleneglycol acrylate, phenoxypolyethyleneglycol methacrylate, 2-glucosyloxyethyl methacrylate;
acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, crotonic acid, methacrylamide, allyl alcohol, N-vinylpyrrolidone, N,N-dimethylaminoethyl acrylate;

Specific examples of monomers having a carboxyl group or a group that can be easily converted to a carboxyl base in the side chain include:
1-methoxyethyl acrylate, 1-ethoxyethyl acrylate, 1-propoxyethyl acrylate, 1-(1-methylethoxy)ethyl acrylate, 1-butoxyethyl acrylate, 1-(2-methylpropoxy)ethyl acrylate, 1-(2 - ethylhexoxy) ethyl acrylate;
pyranyl acrylate, 1-methoxyethyl methacrylate, 1-ethoxyethyl methacrylate, 1-propoxyethyl methacrylate, 1-(1-methylethoxy)ethyl methacrylate, 1-butoxyethyl methacrylate, 1-(2-methyl propoxy)ethyl methacrylate, 1-(2-ethylhexoxy)ethyl methacrylate;
pyranyl methacrylate, di-1-methoxyethyl maleate, di-1-ethoxyethyl maleate, di-1-propoxyethyl maleate, di-1-(1-methylethoxy)ethyl maleate, di-1-butoxyethyl Malate, di-1-(2-methylpropoxy)ethyl maleate, dipyranyl maleate; and the like.

The monomers used for forming the polymer chains described above may be used singly or in combination of two or more.

Further, the monomer used for forming the polymer chain has excellent affinity with the above-described salt-hydrogen bond donor mixture, can further reduce the coefficient of friction of the polymer brush layer 20, and has excellent low friction sliding properties. It is preferable to use a monomer having an ionic dissociation group (especially a monomer having an ionic dissociation group and a reactive double bond group). By using a monomer having an ionic dissociation group, the polymer chain obtained by polymerization can have an ionic dissociation group. As the monomer for forming the polymer chain, in addition to the monomer having an ionic dissociation group, a monomer copolymerizable therewith (for example, each of the monomers described above) may be used. Monomers having such an ionic dissociative group are not particularly limited, but include, for example, compounds represented by the following general formula (4).

In general formula (4) above, R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R ¹² to R ¹⁴ represent alkyl groups having 1 to 5 carbon atoms. R ¹² to R ¹⁴ may contain one or more heteroatoms selected from an oxygen atom, a sulfur atom and a fluorine atom, and R ¹² to R ¹⁴ are bonded to each other to form a ring together with the nitrogen atom to which they are bonded. may be formed. Also, Z ⁻ represents a monovalent anion. In general formula (4) above, k represents an integer of 1 to 10, and j represents an integer of 1 to 5.

In the above general formula (4), the monovalent anion represented by Z ⁻ is not particularly limited, but BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ − , SbF ₆ ⁻ , AlCl ₄ ^{− ,} NbF ₆ ⁻ , Using anions such as HSO ₄ ⁻ , ClO ₄ ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , CF ₃ CO ₂ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , Cl ⁻ , Br ⁻ , I ⁻ These can be used alone or in combination of two or more, but the degree of dissociation and stability in the salt-hydrogen bond donor mixture when swollen with the above-mentioned salt-hydrogen bond donor mixture BF ₄ ⁻ , PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , CF ₃ SO ₃ ⁻ , or CF ₃ CO ₂ ⁻ is more preferable in consideration of mobility and the like.

Among the compounds represented by the general formula (4), from the viewpoint that the effect of reducing the coefficient of friction of the polymer brush layer 20 is greater, the compounds represented by the following general formulas (5) to (12) are particularly preferred. It can be used preferably. In addition, these can be used individually by 1 type or in combination of 2 or more types.

In general formulas (5) to (12) above, R ¹¹ , R ¹² , Z ⁻ , k and j are the same as in general formula (4) above.

Further, when the polymerization is performed by the surface-initiated living radical polymerization method, the polymerization initiating group to be introduced onto the surface of the substrate 10 is not particularly limited as long as it can initiate polymerization. Groups and the like are preferred.

The polymerization initiation group is physically or chemically bonded to the surface of the substrate 10 from the viewpoint of controllability of the graft density and the primary structure (molecular weight, molecular weight distribution, monomer arrangement pattern) of the grafted polymer chain. is preferred.

Methods for introducing (bonding) the polymerization initiation group to the surface of the substrate 10 include a chemical adsorption method, a Langmuir-Blodgett (LB) method, and the like.

For example, when a silicon wafer is used as the substrate 10, 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane is immobilized on the surface of the silicon wafer by chemical bonding of a chlorosulfonyl group (polymerization initiation group). , 2-(4-chlorosulfonylphenyl)ethyltrichlorosilane or the like is used to react with the oxide layer on the surface of the silicon wafer.

Further, when introducing a polymerization initiation group for surface-initiated living radical polymerization to the surface of the base material 10, the polymerization initiation group and a group having bonding property to the base material or a group having affinity for the base material are provided. It is preferable to use a surface treatment agent containing a polymerization initiation group. Such a polymerization initiation group-containing surface treatment agent may be a low-molecular-weight compound or a high-molecular-weight compound.

The surface treatment agent containing a polymerization initiating group is not particularly limited, but a compound having a group capable of bonding to the substrate 10 and a radical generating group is preferable. Initiating group-containing surface treating agents, that is, TEMPO-based, ATRP-based, RAFT-based, and RTCP-based polymerization initiating group-containing surface treating agents can be used. Among these, TEMPO-based, RAFT-based, and RTCP-based polymerization initiation group-containing surface treatment agents are more preferable. Among TEMPO-based surface treating agents containing a polymerization initiating group, DEPN-based surface treating agents containing a polymerization initiating group are particularly preferred. Examples of groups that can be bonded to the substrate 10 include -SiCl ₃ , -Si(CH ₃ )Cl ₂ , -Si(CH ₃ ) ₂ Cl, and -Si(OR') ₃ (in these formulas, R' represents a methyl group, an ethyl group, a propyl group or a butyl group.) and the like. Alternatively, the polymerization initiation group-containing surface treatment agent is described in WO 2006/087839, (2-bromo-2-methyl)propionyloxyhexyltriethoxysilane (BHE), (2-bromo-2 -methyl)propionyloxypropyltriethoxysilane (BPE) and the like can also be used.

Further, from the viewpoint of adjusting the graft density, a silane coupling agent containing no polymerization initiation group (for example, a commonly used alkylsilane coupling agent) may be used in combination with the polymerization initiation group-containing surface treatment agent. good.

The graft density can be freely changed by adjusting the ratio of the polymerization initiation group-containing surface treatment agent and the silane coupling agent containing no polymerization initiation group. In introducing the polymerization initiation group to the surface of the base material 10, the LB method or the vapor phase adsorption method may be adopted from the viewpoints of the uniformity of the polymerization initiation group to be introduced and the controllability of the graft density of the polymerization initiation group. is also possible.

In the LB method, first, a film-forming material is dissolved in a suitable solvent (eg, chloroform, benzene, etc.). Next, after spreading a small amount of this solution on a clean liquid surface, preferably a pure water surface, the solvent is allowed to evaporate or diffuse into the adjacent aqueous phase, resulting in a low density film-forming molecule on the water surface. to form a film of

The diaphragm is then typically mechanically swept over the water surface to compress the membrane by reducing the surface area of the water surface over which the membrane-forming molecules are deployed, thereby increasing the density and forming a dense monolayer on the water surface. get

Next, under appropriate conditions, while maintaining a constant surface density of the molecules that make up the monomolecular film on the water surface, the substrate on which the monomolecular layer is to be deposited is immersed or pulled up in a direction across the monomolecular film on the water surface. transfers the monomolecular film on the water surface onto the substrate 10 and deposits a monolayer on the substrate.

For details and specific examples of the LB method, see Kiyonari Fukuda et al., New Experimental Chemistry Course, Volume 18 (Interface and Colloid), Chapter 6, (1977) Maruzen, Edited by Kiyonari Fukuda, Michio Sugi and Hiroyuki Sasabe, LB Membrane and Electronics, (1986) CMC", "Yoshio Ishii, Practical Techniques for Producing Good LB Films, (1989) Kyoritsu Shuppan".

Then, a polymerization initiation group is introduced into the surface of the base material 10 by using the above-described method of using the polymerization initiation group-containing surface treatment agent, and then the base material 10 introduced with the polymerization initiation group is coated with the above-described monomer. By immersing the substrate 10 in the polymerization reaction solution and heating as necessary, polymer chains containing the above-described monomers as polymerization units can be formed on the surface of the substrate 10 . In addition to the monomers described above, the polymerization reaction solution can contain various components necessary for the polymerization reaction, such as various radical initiators and solvents.

In the first embodiment, the polymer chains formed on the surface of the base material 10 are formed with a graft density such that the exclusive area ratio (occupancy rate per polymer cross-sectional area) with respect to the surface area of the base material 10 is 10% or more. preferably 15% or more, and still more preferably 20% or more. The graft density can be calculated from, for example, the absolute value of the number average molecular weight (Mn) of graft chains, the amount of grafted polymer, and the surface area of substrate 10 . Further, the exclusive area ratio in the polymer brush layer 20 can be calculated by obtaining the cross-sectional area from the length of the repeating unit in the stretched form of the polymer and the bulk density of the polymer, and multiplying the cross-sectional area by the graft density. The occupied area ratio means the ratio of the surface of the base material 10 occupied by the graft points (the first monomer) (100% in close packing, no more grafting is possible).

In addition, the graft density per unit area of the polymer chains is preferably 0.02 chains/nm ² or more, more preferably 0.04 chains/nm ² or more, still more preferably 0.06 chains/nm ² or more, particularly It is preferably 0.08 chains/nm2 ^or more.

The graft density of the polymer chain can be determined, for example, according to the method described in Macromolecules, 31, 5934-5936 (1998), Macromolecules, 33, 5608-5612 (2000), Macromolecules, 38, 2137-2142 (2005), etc. can be measured. Specifically, the graft density (chains/nm ² ) can be obtained by measuring the graft amount (W) and the number average molecular weight (Mn) of the grafted chains and using the following formula.
Graft density (chain/nm ² ) = W (g/nm ² )/M n x (Avogadro's number)
(In the formula, W represents the amount of grafting and Mn represents the number average molecular weight.)

When the base material 10 is a flat substrate such as a silicon wafer, the graft amount (W) is obtained by measuring the dry film thickness, that is, the dry film thickness of the grafted polymer chain layer by ellipsometry. , can be obtained by calculating the graft amount per unit area using the density of the bulk film. Alternatively, when the base material 10 is silica particles or the like, it can be measured by infrared absorption spectrometry (IR), thermogravimetric loss measurement (TG), elemental analysis measurement, or the like.

The number average molecular weight (Mn) of the polymer chains constituting the polymer brush layer 20 is preferably 500 to 10,000,000, more preferably 100,000 to 10,000,000. In addition, the molecular weight distribution (Mw/Mn) of the polymer chains forming the polymer brush layer 20 can further reduce the friction coefficient of the polymer brush layer 20, and from the viewpoint of making the polymer brush layer 20 more excellent in low-friction slidability, It is preferably close to 1, preferably 1.5 or less, more preferably 1.3 or less, still more preferably 1.25 or less, even more preferably 1.2 or less, particularly preferably 1.15 or less. is. The number average molecular weight (Mn) and the molecular weight distribution (Mw/Mn) of the polymer chains are obtained, for example, by cutting out the polymer chains from the base material 10 by hydrofluoric acid treatment and subjecting the cut polymer chains to gel permeation. A method of measuring with a value converted to polyethylene oxide by a chromatographic method can be mentioned. Alternatively, assuming that the free polymer generated during polymerization has the same molecular weight as the polymer chain introduced into the base material 10, the free polymer is subjected to gel permeation chromatography, and the number average A method of measuring the molecular weight (Mn) and the molecular weight distribution (Mw/Mn) and using them as they are may be employed.

The average molecular chain length L _p (that is, the polymer brush length) of the polymer chains constituting the polymer brush layer 20 is preferably 10 nm or more, and from a practical point of view, it should be in the range of 10 to 1000 nm. is more preferred. If the average molecular chain length _Lp of the polymer chain is too short, the sliding properties may become insufficient. Also, the average molecular chain length _Lp of the polymer chain can be adjusted by, for example, the type of monomers constituting the polymer chain, polymerization conditions, and the like.

In the first embodiment, the method for swelling the plurality of polymer chains formed on the substrate 10 with the salt-hydrogen bond donor mixture is not particularly limited. A method in which a salt-hydrogen bond donor mixture is dropped or applied onto the polymer chains and then allowed to stand, or a method in which the substrate 10 on which a plurality of polymer chains are formed is immersed in the salt-hydrogen bond donor mixture. etc.

The thickness of the polymer brush layer 20 formed according to the first embodiment is preferably 500 nm or more from the viewpoint that the coefficient of friction of the polymer brush layer 20 can be further reduced and the low-friction slidability can be further improved. is 700 nm or more, more preferably 800 nm or more, and still more preferably 1,000 nm or more. Although the upper limit of the thickness of the polymer brush layer 20 is not particularly limited, it is usually 20 μm or less.

<Second embodiment>
Next, a second embodiment of the invention will be described.
The composite material according to the second embodiment has the same configuration as that of the first embodiment except that the plurality of polymer chains constituting the polymer brush layer 20 shown in FIG. 1 form a crosslinked network structure. It is. That is, in the second embodiment, a plurality of polymer chains covalently fixed on the substrate 10 as a substrate form a crosslinked network structure, and such a crosslinked network structure is formed. The polymer chains are swollen with the salt-hydrogen bond donor mixture described above to form the polymer brush layer 20 . Also in the second embodiment, the plurality of polymer chains may be a plurality of polymer graft chains.

The polymer chains forming the crosslinked network structure that constitute the polymer brush layer 20 are not particularly limited. A double network gel that forms an interpenetrating network structure is preferred. Here, the term "interpenetrating network structure" means that polymers having two or more crosslinked network structures are physically entangled by entering each other's network structure, resulting in the formation of multiple network structures inside. A structure or state in which In addition, the double network gel according to the second embodiment is formed of not only two types of polymer networks, but also three types of polymer networks, or more types of polymer networks. can be any of the The double network gel according to the second embodiment may further contain a linear polymer to form a semi-interpenetrating network structure.

The two or more types of polymer networks for forming the double network gel are not particularly limited. From the point of view, a polymer network (A) formed from unsaturated monomers having groups that can be positively or negatively charged and unsaturated monomers that are electrically neutral (having no groups that can be positively or negatively charged) It is preferably a combination with a polymer network (B) formed from.

A positively or negatively charged polymer network (A) formed from unsaturated monomers having groups that can be positively or negatively charged (hereinafter referred to as "polymer network (A)" as appropriate). Unsaturated monomers having groups to obtain are not particularly limited, but include unsaturated monomers having acidic groups (e.g., carboxyl groups, phosphoric acid groups and sulfonic acid groups) and basic groups (e.g., amino groups). .

Specific examples of unsaturated monomers having groups that can be positively or negatively charged include:
(Meth)acrylic acid (meaning acrylic acid and/or methacrylic acid; hereinafter the same), (anhydrous) maleic acid, maleic acid monoalkyl ester, fumaric acid, fumaric acid monoalkyl ester, crotonic acid, itaconic acid, itaconic acid carboxyl group-containing vinyl monomers such as acid monoalkyl esters, itaconic acid glycol monoethers, citraconic acid, citraconic acid monoalkyl esters, cinnamic acid, and salts thereof;
sulfopropyl (meth)acrylate, 2-hydroxy-3-(meth)acryloxypropylsulfonic acid, 2-(meth)acryloylamino-2,2-dimethylethanesulfonic acid, 2-(meth)acryloyloxyethanesulfonic acid, 3-(meth)acryloyloxy-2-hydroxypropanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and other sulfonic acid group-containing vinyl monomers, and salts thereof;
Phosphate group-containing vinyl monomers such as 2-hydroxyethyl acryloyl phosphate, and salts thereof;
amino group-containing vinyl monomers such as aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate; and the like.
These monomers may be used singly or in combination of two or more.

Further, a polymer network (B) formed from electrically neutral unsaturated monomers (having no positively or negatively charged groups) (hereinafter referred to as "polymer network (B)" as appropriate). Electrically neutral unsaturated monomers for forming include dimethylsiloxane, styrene, acrylamide, methylenebisacrylamide, trimethylpropane trimethacrylate, vinylpyridine, styrene, methyl methacrylate, fluorine-containing unsaturated monomers ( Examples include trifluoroethyl acrylate (TFE)), hydroxyethyl acrylate, vinyl acetate, triethylene glycol dimethacrylate, and the like. These monomers may be used singly or in combination of two or more.

In the second embodiment, from the viewpoint that the strength of the double network gel can be appropriately increased when swollen with a salt-hydrogen bond donor mixture, the double network gel is a polymer having a relatively large molecular weight between crosslinks. A combination of a network and a polymer network having a relatively small molecular weight between cross-linking points is preferable, and in particular, from the viewpoint of improving affinity with the salt-hydrogen bond donor mixture, in the first embodiment. A combination of a polymer network (C) formed from the compound represented by the above general formula (4) and a polymer network (D) formed from a compound other than the compound represented by the above general formula (4) is preferably

The compound represented by the general formula (4) used to form the polymer network (C) is represented by the general formulas (5) to (12) as in the first embodiment. Compounds can be particularly preferably used, and these can be used singly or in combination of two or more.

Moreover, the monomer for forming the polymer network (D) is not particularly limited, and examples thereof include electrically neutral unsaturated monomers used for forming the polymer network (B) described above.

A method for forming the polymer brush layer 20 on the substrate 10 when the plurality of polymer chains formed on the substrate 10 is a double network gel is not particularly limited, but the method described below can be mentioned. be done. In addition, the case where the polymer network which comprises a double network gel is made into two types below is illustrated and demonstrated.

First, a compound for introducing a substituent capable of reacting with the radical active species is reacted with the surface of the substrate 10 to the surface of the substrate 10, and a substituent capable of reacting with the radical active species is formed on the surface of the substrate 10. introduce a group. The compound for introducing the substituent capable of reacting with the radical active species is not particularly limited, but preferably includes a compound containing a substituent capable of reacting with the radical active species and an alkoxysilyl group.

Compounds containing substituents and alkoxysilyl groups capable of reacting with radical active species are not particularly limited, but N,N-bis(3-(trimethoxysilyl)propyl)methacrylamide, N,N-bis(3 -(trimethoxysilyl)propyl)acrylamide, N,N-bis((methyldimethoxysilyl)propyl) alkoxysilyl group-containing amide compounds having unsaturated bonds such as methacrylamide; 3-(trimethoxysilyl)propyl methacrylate, Alkoxy such as 3-(triethoxysilyl)propyl methacrylate, 3-[tri(methoxyethoxy)silyl]propyl methacrylate, 3-(methyldimethoxysilyl)propyl methacrylate, 3-(methyldiethoxysilyl)propyl methacrylate, etc. silyl group-containing acrylate compounds; and the like.

The method of reacting the surface of the base material 10 with a compound containing a substituent and an alkoxysilyl group capable of reacting with a radically active species is not particularly limited. and immersing the substrate 10, which has been subjected to hydrophilization treatment, in a solution containing a compound containing a substituent and an alkoxysilyl group that can react with radical active species, thereby reacting them, and the like. . The hydrophilization treatment method is not particularly limited, but includes a plasma etching treatment method and the like.

The reaction temperature at this time is not particularly limited, but is preferably 20 to 50° C., and the reaction time is 6 to 48 hours.

Next, separately from the above, a gel (hereinafter referred to as "first polymer network gel”) is prepared. The method for producing the first polymer network gel is not particularly limited, but a solution containing a monomer for forming the first polymer network gel, a cross-linking agent, and a salt-hydrogen bond donor mixture is prepared, and the solution is polymerized. and cross-linking.

The cross-linking agent is not particularly limited as long as it can form a cross-linked structure. Examples include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate. , divinylbenzene and methylenebisacrylamide.

Next, a monomer for forming the remaining polymer network (hereinafter referred to as "second polymer network") of the two types of polymer networks in the first polymer network gel obtained above, and a cross-linking agent is impregnated into the first polymer network gel, thereby preparing a monomer-containing first polymer network gel. At this time, the solution impregnated into the first polymer network gel may further contain a salt-hydrogen bond donor mixture.

The method for impregnating the first polymer network gel with the solution containing the monomer for forming the second polymer network and the cross-linking agent is not particularly limited. A method of immersing a network gel and the like can be mentioned. As the cross-linking agent, those mentioned above can be used in the same manner.

Next, the monomer-containing first polymer network gel obtained as described above is brought into contact with the base material 10 having a substituent capable of reacting with the radical active species introduced to the surface thereof, and reacted while they are in contact. Thereby, the second polymer network is formed by the second polymer network-forming monomer contained in the monomer-containing first polymer network gel, and the second polymer network-forming monomer is introduced onto the substrate 10. A polymer brush layer in which a polymer chain composed of a double network gel is swollen with a salt-hydrogen bond donor mixture is formed on the substrate 10 by allowing the reaction between the radical active species and the reactive substituent to proceed simultaneously. 20 can be formed.

Also in the second embodiment, as in the first embodiment described above, the salt-hydrogen bond donor described above is used as a swelling agent for swelling the polymer chains forming the crosslinked network structure, which constitutes the polymer brush layer 20 . Since a mixture is used, the coefficient of friction of the polymer brush layer 20 can be reduced, and excellent low-friction slidability can be achieved.

<Third Embodiment>
Next, a third embodiment of the invention will be described.
FIG. 2 shows a branched polymer forming a composite material according to the third embodiment of the present invention. As shown in FIG. 2, a branched polymer 30 according to the third embodiment comprises a linear main chain (a linear polymer chain serving as a main chain) 31 as a substrate, and a plurality of polymer graft chains. The (side chain) 32 has a branched structure, and the composite material according to the third embodiment is constructed by swelling such a branched polymer 30 with the salt-hydrogen bond donor mixture described above. be. The branched polymer 30 has a shape like a bottle brush (a cleaning brush for cleaning a container having a bottle structure).

The branched polymer 30 has a branched polymer structure in which a plurality of side chains 32 are branched from the linear main chain 31 as described above. It is composed of a plurality of repeating units containing carbon atoms and hydrogen atoms linked together.

The number average degree of polymerization of the main chain 31 is preferably 10-10,000, more preferably 10-1,000, still more preferably 10-100. By setting the number-average degree of polymerization of the main chain 31 within the above range, the low-friction slidability can be further enhanced in the case of swelling with the above-mentioned salt-hydrogen bond donor mixture to form a composite material. The number average degree of polymerization of the main chain 31 is not particularly limited, but the number average molecular weight of the main chain precursor before introducing the side chain 32 is measured, and the measured number average molecular weight is divided by the monomer unit molecular weight. can be found at

The side chain 32 may be linear, or may have a branched structure or a crosslinked structure. The number average degree of polymerization of the side chains 32 is preferably 1-1,00, more preferably 1-50, and even more preferably 5-20. By setting the number-average degree of polymerization of the side chains 32 within the above range, the low-friction slidability can be further enhanced in the case of swelling with the above-mentioned salt-hydrogen bond donor mixture to form a composite material. The method for measuring the number average degree of polymerization of the side chain is not particularly limited. A small amount of an agent (for example, an organic compound having a halogen-substituted carbon group) is added to simultaneously synthesize a free polymer having a repeating structure common to the polymer chain of the side chain 32, and the free polymer is measured. The obtained number average degree of polymerization can be used as the number average degree of polymerization of the side chain 32 .

The number average molecular weight (Mn) of the entire branched polymer 30 including the main chain 31 and side chains 32 is preferably 1,000 to 10,000,000, more preferably 1,000 to 1,000,000. , more preferably 5,000 to 500,000. By setting the number-average molecular weight of the entire branched polymer 30 within the above range, it is possible to further enhance the low-friction slidability in the case of swelling with the above-mentioned salt-hydrogen bond donor mixture to form a composite material. The number average molecular weight of the branched polymer 30 as a whole can be measured by a gel permeation chromatography method in terms of polystyrene.

The density of side chains branched from the main chain is the number per 1 nm of main chain path length (chain/nm), preferably 1 chain/nm or more, more preferably 2 chains/nm or more, and still more preferably 3 chains. /nm or more. Here, the density of side chains can be determined from the graft efficiency.

As the branched polymer 30 used in the third embodiment, as shown in FIG. 2, any structure may be used as long as it has a structure in which a plurality of side chains 32 are branched from a linear main chain 31 as a substrate. Although not limited, it is preferably a compound represented by the following general formula (13).

In general formula (13) above, R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a methyl group, R ¹⁷ represents an alkyl group having 1 to 10 carbon atoms, and R ¹⁸ and R ¹⁹ are A terminal group composed of an atom or an atomic group, and includes a hydrogen atom, an azide group, a fragment of a polymerization initiation group, a polymerization control group, and the like. Further, Q ¹ represents -O- or -NH-, Q ² represents a divalent organic group, h is 10 to 10,000, and Polymer A represents a polymer chain. In the compound represented by the above general formula (13), the parenthesized repeating structural unit having h of repeating units corresponds to the main chain 31 of the branched polymer 30, and Polymer A corresponds to the branched polymer 30. corresponds to the side chain 32 of That is, in the compound represented by the above general formula (13), from the carbon atom to which R ¹⁵ is bonded to the carbon atom to which Polymer A is bonded, via a predetermined organic group, the main consisting of h repeating units It has a configuration in which a plurality of side chains 32 represented by Polymer A are linked to a chain 31 . In general formula (13) above, Polymer A may be introduced into all the repeating units constituting the compound represented by general formula (13) above, or may be introduced into only some of the repeating units. may be When Polymer A is introduced into only a part of the repeating units constituting the compound represented by the general formula (13), the terminal of the side chain of the repeating unit into which Polymer A is not introduced is a hydrogen atom. It may be one in which the polymerization initiation group remains, or one in which the hydrogen atom or the polymerization initiation group is replaced with another atom or atomic group.

Q ² is a divalent organic group and is an alkylene group having 1 to 18 carbon atoms or an oxyalkylene group having 1 to 10 carbon atoms (R ²⁰ O) (R ²⁰ represents an alkylene group having 1 to 18 carbon atoms). ), a linked structure in which a plurality of oxyalkylene groups are linked, or at least one of these organic groups (alkylene group having 1 to 18 carbon atoms, oxyalkylene group having 1 to 10 carbon atoms, and linked structure of oxyalkylene group) A divalent organic group consisting of a combination of two groups and the like can be mentioned. Here, the alkylene group of the alkylene group and the oxyalkylene group may be linear or branched, and may have a cyclic structure. Specific examples of the alkylene group include ethylene group, propylene group, butylene group and cyclohexylene group. The alkylene group of this alkylene group and oxyalkylene group may be substituted with a substituent. Examples of substituents include alkyl groups having 1 to 10 carbon atoms, aryl groups having 6 to 40 carbon atoms, and heteroaryl groups having 3 to 40 carbon atoms, and these substituents are further substituted with substituents. good too.

In general formula (13) above, Polymer A preferably has a structural unit derived from a (meth)acrylic acid-based monomer. (Meth) acrylic acid-based monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, 2-methylpropyl (meth) acrylate. , t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate ) acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, octadecyl (meth)acrylate, behenyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate , isobornyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, cyclodecyl (meth)acrylate, cyclodecylmethyl (meth)acrylate, tricyclodecyl (meth)acrylate, benzyl (meth)acrylate, dicyclopentenyloxyethyl (meth) (cyclo)alkyl (meth)acrylates such as acrylate and dicyclopentanyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate and naphthyl (meth)acrylate; alkenyl (meth)acrylates such as allyl (meth)acrylate; ) acrylates; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, (poly)ethylene glycol mono(meth)acrylate; (poly)ethylene glycol monomethyl ether (meth) Glycol monoalkyl ethers such as acrylates, (poly)ethylene glycol monoethyl ether (meth)acrylate, (poly)ethylene glycol monolauryl ether (meth)acrylate, (poly)propylene glycol monomethyl ether (meth)acrylate, etc. ) acrylate; (meth)acrylic acid, mono-2-((meth)acryloyloxy)ethyl phthalate, mono-2-((meth)acryloyloxy)ethyl succinate, mono-2-((meth)acryloyloxy) hexahydrophthalate ) Ethyl, carboxyl group-containing (meth)acrylates such as mono-2-((meth)acryloyloxy)ethyl trimellitate; (meth)acrylates containing acid groups other than groups; amino group-containing (meth)acrylates such as dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate and t-butylaminoethyl (meth)acrylate; chlorotrimethylammonium (meth)acrylates having a quaternary ammonium base such as ethyl (meth)acrylate; the isocyanate groups of (meth)acryloyloxyethyl isocyanate and 2-(2-isocyanatoethoxy)ethyl (meth)acrylate to ε-caprolactone, Methyl ethyl ketone oxime (MEK oxime), and isocyanate group-containing (meth) acrylates blocked with pyrazole, etc.; cyclic (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate; octafluorooctyl (meth) acrylate, tetrafluoroethyl (meth) Halogen-containing (meth)acrylates such as acrylate; 2-(4-benzoxy-3-hydroxyphenoxy)ethyl (meth)acrylate, 2-(2'-hydroxy-5-(meth)acryloyloxyethylphenyl)-2H- UV-absorbing (meth)acrylates such as benzotriazole; silicon-containing (meth)acrylates having a trimethoxysilyl group or a dimethylsilicone chain; A macromonomer obtained by introducing a (meth)acrylic group to one end of an oligomer obtained by polymerizing these monomers can also be used.

Polymer A may be a homopolymer, a copolymer having a random structure, or a copolymer having a block structure.

上記一般式（１４）、（１５）において、Ｒ^１５、Ｒ^１６、Ｒ^１７、Ｒ^１８、Ｒ^１９、Ｑ^１、Ｑ^２、ｈは、上記一般式（１３）と同様である。 The compound represented by the general formula (13) is, for example, a polymer (initiating group-containing polymer) of a monomer represented by the following general formula (14), from a compound represented by the following general formula (15) Polymer A can be obtained by using a carbon radical generated by elimination of the group represented by T ¹ as an active site and grafting a polymer chain therefrom to generate Polymer A. Here, a compound represented by the following general formula (15) containing a polymerization initiating group (T ¹ ) (a polymer before introducing Polymer A) is referred to as an "initiating group-containing polymer", and the polymerization initiating group Radicals generated by the reaction of are sometimes referred to as "active sites".

In general formulas (14) and (15) above, R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ , Q ¹ , Q ² and h are the same as in general formula (13) above.

The monomer represented by the general formula (14) is, for example, a reaction of a (meth)acrylate having a hydroxyl group (hereinafter referred to as "monomer (a)" and an acid component (hereinafter referred to as "acid component (b)"). can be synthesized by

Among the monomers (a), examples of compounds that produce monomers in which Q ¹ in the general formula (14) is —O— include 2-hydroxyethyl (meth)acrylate and 2-(meth)acrylate. Hydroxypropyl, 3-hydroxypropyl (meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, 2-hydroxy-3-chloropropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, ( hydroxycyclohexyl meth)acrylate, polyethylene glycol (meth)acrylate monoester, propylene glycol (meth)acrylate monoester, ethylene propylene glycol (meth)acrylate and the like.
Among the monomers (a), examples of compounds that generate monomers (a) in which Q ¹ in the general formula (14) is —NH— include hydroxyethyl (meth)acrylamide; (meth)acrylic acid and (meth)acryl A monomer obtained by reacting an acid halide such as an acid chloride with a compound having an amino group and one or more hydroxyl groups, and the like.
Examples of acid component (b) include 2-chloropropionic acid, 2-bromopropionic acid, 2-chloro-2-methyl-propionic acid, 2-bromo-2-methyl-propionic acid and the like. Moreover, these acid halides, acid anhydrides, etc. can also be used as an acid component (b).

The compound represented by the general formula (15) can also be obtained by reacting the polymer of the monomer (a) with the acid component (b).

As the branched polymer 30, instead of the compound represented by the general formula (13), the above acid component ( It is also possible to use a product obtained by reacting b) and then reacting this with Polymer A.

Further, in the third embodiment, as the branched polymer 30, a plurality of branched polymers 30 forming a crosslinked structure may be used, or the plurality of branched polymers 30 may be composed of ionic bonds, Those bonded to each other by hydrogen bonding, hydrophobic interaction, or the like may be used. Alternatively, a base material or filler is used, a polymerization initiating group is introduced to the surface of the base material or filler, and a polymerization reaction is performed on the base material or in a state containing the filler to obtain a branched polymer. 30 may be on a substrate or composited with a filler.

A composite material according to the third embodiment can be obtained by swelling such a branched polymer 30 with the salt-hydrogen bond donor mixture described above. The method for swelling the branched polymer 30 with the salt-hydrogen bond donor mixture is not particularly limited. and immersing the branched polymer 30 in a salt-hydrogen bond donor mixture.

Also in the third embodiment, as in the first embodiment described above, a salt-hydrogen bond donor mixture is used as a swelling agent for swelling the branched polymer 30, so excellent low friction sliding property can be realized.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
(Preparation of salt-hydrogen bond donor mixture (A-1))
6.981 g (1 mol) of choline chloride (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 302 to 305° C.) and 6.006 g (2 mol) of urea (manufactured by Kishida Chemical Co., Ltd., melting point: 133 to 135° C.) were dissolved in 10 g of methanol and mixed at a temperature of 70° C. to obtain a mixed liquid. Next, the resulting mixture was depressurized with a vacuum pump to remove methanol, thereby obtaining a salt-hydrogen bond donor mixture (A-1) containing choline chloride and urea. The resulting salt-hydrogen bond donor mixture (A-1) was a colorless and transparent liquid at room temperature (25°C), with a melting point of 12°C.

(Formation of polymer chains on the surface of a silicon substrate by surface-initiated living radical polymerization)
3-((3-(Triethoxysilyl)propyl)thio)propyl-2-bromo-2-methylpropanoate (BPTPE) as an immobilized initiator and ethanol were mixed, and then aqueous ammonia was added thereto. An immobilized initiator-containing solution was prepared by mixing ethanol containing Then, the silicon substrate was immersed in the immobilized initiator-containing solution prepared above for 18 hours to prepare a silicon substrate having a polymerization initiation group introduced on its surface.

In addition to the above, as a monomer having an ionic dissociation group (ionic liquid monomer), N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEMM-TFSI), ethyl-2-bromo-2-methylpropionate (EBIB) as radical initiator, 2,2-bipyridyl 0.020 g as ligand, CuCl as copper catalyst, with acetonitrile. A monomer solution was obtained by mixing.

The resulting monomer solution was applied to the surface of the silicon substrate into which the polymerization initiation group had been introduced, and heated in an incubator under an argon atmosphere at 70° C. for 32 hours. The resulting substrate was subjected to ultrasonic cleaning in acetonitrile for 10 minutes, and this was repeated three times to clean the polymerization solution. A silicon substrate with chains was obtained. In addition, when the number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the free polymer jointly obtained in the synthesis system were measured at this time, Mn = 1,431, 500, Mw=1,702,600, Mw/Mn=1.189, and thickness 400 nm.

(Formation of polymer brush layer)
Then, the salt-hydrogen bond donor mixture (A-1) obtained above is applied to the surface of the silicon substrate to which the polymer chains obtained above are introduced, onto which the polymer chains are introduced, Soaking for 24 hours swelled the polymer chains to yield a silicon substrate with a polymer brush layer (dense polymer brush swollen with salt-hydrogen bond donor mixture). The thickness of the formed polymer brush layer was 1-1.2 μm.

(friction test)
Ball-on-disk friction tests were performed using a silicon substrate of dense polymer brushes swollen with the salt-hydrogen bond donor mixture obtained above on the disk side and glass spheres (10 mm diameter) on the ball side. Specifically, it was set in a friction wear tester "TRIBOGEAR, TYPE38" (manufactured by Shinto Kagaku Co., Ltd.) to measure the frictional force. The measurement conditions were as follows: sliding velocity at 6 points of 0.5, 1, 5, 10, 30, and 50 mm/s, sliding distance of 10 mm, constant load of 1 N, test temperature of 25°C, test humidity of 30%, and reciprocating linear motion test. . The results are shown in FIG. In FIG. 3, the obtained results are shown with the horizontal axis as "sliding speed/load (unit: "m/N·sec")" and the vertical axis as "friction coefficient".

<Example 2>
(Preparation of salt-hydrogen bond donor mixture (A-2))
Choline chloride (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 302 to 305 ° C.) 4.6540 g (1 mol) and ethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: -12.9 ° C.) 6.2070 g ( 2 mol) at a temperature of 70° C. to obtain a salt-hydrogen bond donor mixture (A-2) containing choline chloride and ethylene glycol. The resulting salt-hydrogen bond donor mixture (A-2) was a colorless transparent liquid at room temperature (25°C), and had a melting point of -66°C.

(Formation of polymer brush layer, friction test)
Next, the salt-hydrogen bond donor mixture obtained above (A-2 ) was applied and soaked for 24 hours to swell the polymer chains to obtain a silicon substrate on which a polymer brush layer was formed (dense polymer brush swollen with salt-hydrogen bond donor mixture). The thickness of the formed polymer brush layer was 1-1.2 μm.
Then, a friction test was performed in the same manner as in Example 1 on the dense polymer brush swollen with the salt-hydrogen bond donor mixture obtained above. The results are shown in FIG.

<Example 3>
(Preparation of salt-hydrogen bond donor mixture (A-3))
4.6540 g (1 mol) of choline chloride (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 302 to 305° C.) and 9.2090 g (2 mol) of glycerin (manufactured by Kanto Chemical Co., Ltd., melting point: 17.8° C.) were mixed at a temperature of 70° C. to obtain a salt-hydrogen bond donor mixture (A-3) containing choline chloride and glycerin. The resulting salt-hydrogen bond donor mixture (A-3) was a colorless transparent liquid with a melting point of -40°C at room temperature (25°C).

(Formation of polymer brush layer, friction test)
Next, the salt-hydrogen bond donor mixture obtained above (A-3 ) and soaked for 24 hours to swell the polymer chains to obtain a silicon substrate with a polymer brush layer (dense polymer brush swollen with salt-hydrogen bond donor mixture). The thickness of the formed polymer brush layer was 1-1.2 μm.
Then, a friction test was performed in the same manner as in Example 1 on the dense polymer brush swollen with the salt-hydrogen bond donor mixture obtained above. The results are shown in FIG.

<Example 4>
(Preparation of salt-hydrogen bond donor mixture (A-4))
4.5427 g (1 mol) of zinc chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., melting point: 275° C.) and 7.0070 g (3. 5 mol) were dissolved in 10 g of methanol and mixed at a temperature of 70° C. to obtain a mixed liquid. Next, the resulting mixture was decompressed with a vacuum pump to remove methanol, thereby obtaining a salt-hydrogen bond donor mixture (A-4) containing zinc chloride and urea. The obtained salt - The hydrogen bond donor mixture (A-4) was a colorless and transparent liquid at room temperature (25° C.) The salt-hydrogen bond donor mixture obtained above had a high viscosity, and as such, meaningful friction measurements could not be performed. Therefore, solutions (A-4-water) and (A-4-MeOH) were prepared by adding 20 wt% of water or MeOH (methanol) as a viscosity adjusting component to lower the viscosity.

(Formation of polymer brush layer, friction test)
Next, the salt-hydrogen bond donor mixture obtained above + the viscosity adjusting component was applied to the surface of the silicon substrate to which the polymer chains had been introduced, which was obtained in the same manner as in Example 1. A mixture of (A-4-water) or (A-4-MeOH) is applied and immersed for 24 hours to swell the polymer chains and form a silicon substrate with a polymer brush layer (salt-hydrogen bond A dense polymer brush swollen with the donor mixture) was obtained. The thickness of each polymer brush layer formed was 1 to 1.2 μm. Then, a friction test was performed in the same manner as in Example 1 on the dense polymer brush swollen with the salt-hydrogen bond donor mixture obtained above. The results are shown in FIG.

<Example 5>
(Preparation of salt-hydrogen bond donor mixture (A-5))
Tetrabutylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 103 ° C.) 6.4476 g (3 mol) and imidazole (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 89 to 91 ° C.) 3.1771 g (7 mol) were weighed and mixed in a mortar while crushing lumps. Next, the resulting mixture was transferred to a glass container and stirred in an oil bath at 70° C. to obtain a salt-hydrogen bond donor mixture (A-5) containing tetrabutylammonium bromide and imidazole. The resulting salt-hydrogen bond donor mixture (A-5) was a colorless transparent liquid at room temperature (25°C).

(Formation of polymer chains on the surface of a silicon substrate by surface-initiated living radical polymerization)
Methyl methacrylate (hereinafter, MMA), ethyl 2-bromo-2-methylpropionate (hereinafter, EBIB), copper (I) bromide (hereinafter, Cu (I) Br) is placed in a Teflon (registered trademark) pressure-resistant container. , copper(II) bromide (hereinafter Cu(II)Br ₂ ), and 4,4′-dinonyl-2,2′-bipyridyl (hereinafter dNbipy) to give (2-bromoisobutyroxy) In the presence of a silicon substrate or a glass disk on which hexyltriethoxysilane (hereinafter referred to as BHE) is immobilized on the surface, surface-initiated living radical polymerization ( SI-ATRP) was performed.

After a predetermined time, the substrate was taken out from the reaction solution, ultrasonically cleaned with tetrahydrofuran (hereinafter referred to as THF), and dried to obtain a silicon substrate having polymer graft chains introduced on the surface of the substrate. When the number average molecular weight (Mn), weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the free polymer jointly obtained in the synthesis system were measured at this time, Mn = 2,010,000, Mw=1,600,000, Mw/Mn=1.26, thickness 1 μm.

(Formation of polymer brush layer, friction test)
Then, the salt-hydrogen bond donor mixture (A-5) obtained above is applied to the surface of the silicon substrate to which the polymer chains obtained above are introduced, onto which the polymer chains are introduced, Soaking for 24 hours swelled the polymer chains to yield a silicon substrate with a polymer brush layer (dense polymer brush swollen with salt-hydrogen bond donor mixture). The thickness of the formed polymer brush layer was 3 μm±1 μm.
Then, a friction test was performed in the same manner as in Example 1 on the dense polymer brush swollen with the salt-hydrogen bond donor mixture obtained above. The results are shown in FIG.

<Example 6>
(Preparation of salt-hydrogen bond donor mixture (A-6))
Tetrabutylphosphonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 100 to 103 ° C.) 6.7868 g (3 mol) and imidazole (manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 89 to 91 ° C.) 3.1771 g (7 mol) were weighed and mixed in a mortar while crushing lumps. Next, the resulting mixture was transferred to a glass container and stirred in an oil bath at 70° C. to obtain a salt-hydrogen bond donor mixture (A-6) containing tetrabutylphosphonium bromide and imidazole. The resulting salt-hydrogen bond donor mixture (A-6) was a colorless transparent liquid at room temperature (25°C).

(Formation of polymer brush layer, friction test)
Next, the salt-hydrogen bond donor mixture obtained above (A-6 ) and soaked for 24 hours to swell the polymer chains to obtain a silicon substrate with a polymer brush layer (dense polymer brush swollen with salt-hydrogen bond donor mixture). The thickness of the formed polymer brush layer was 3 μm±1 μm.
Then, a friction test was performed in the same manner as in Example 1 on the dense polymer brush swollen with the salt-hydrogen bond donor mixture obtained above. The results are shown in FIG.

<Comparative Example 1>
(Formation of polymer brush layer, friction test)
Polyol ester (POE) (manufactured by JX Holdings Co., Ltd. (JXHD)) as a lubricating oil was applied to the surface of the polymer chain-introduced silicon substrate obtained in the same manner as in Example 1. ) was applied and soaked for 24 hours.
Then, a friction test was performed in the same manner as in Example 1 for the thick polymer brush immersed in the lubricating oil obtained above. The results are shown in FIG.

<Comparative Example 2>
Using a silicon substrate into which polymer chains obtained in the same manner as in Example 1 were introduced, instead of the salt-hydrogen bond donor mixture (A-1), N,N-diethyl-N-methyl-N- A polymer brush layer was formed in the same manner as in Example 1 except that (2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide (DEME-TFSI, manufactured by Kanto Kagaku Co., Ltd.) was used, and a friction test was performed. did The results are shown in FIG.

<Evaluation>
As shown in FIG. 3, a composite material in which a plurality of polymer chains fixed to a substrate is swollen with a mixture containing a salt and a hydrogen bond donating compound, the melting point of which is maintained at 100° C. or less , the thick polymer brush has a greatly reduced coefficient of friction compared to the thick polymer brush immersed in lubricating oil. In addition, even when compared with a dense polymer brush immersed in the ionic liquid DEME-TFSI, the result was excellent in low friction. As can be confirmed from FIG. 3, such excellent low friction property was sufficiently achieved even when the "sliding speed/load" was changed. It can be said that excellent low-friction properties can be realized under the conditions.
Further, as shown in FIG. 4, even when a mixture containing a salt and a hydrogen bond donating compound whose melting point is maintained at 100° C. or lower is mixed with water or an ionic liquid for viscosity adjustment, the base does not adhere to the substrate. It can be said that a dense polymer brush, which is a composite material formed by swelling a plurality of fixed polymer chains, can achieve low friction.

Claims (13)

A composite material obtained by swelling a plurality of polymer chains fixed to a substrate with a mixture containing a salt and a hydrogen bond donating compound, the melting point of which is maintained at 100° C. or lower,
The salt is an organic salt that is solid at normal temperature (25° C.),
The composite material, wherein the mixture has a melting point lower than the melting point of the salt constituting the mixture and the melting point of the hydrogen bond donating compound constituting the mixture. 2. The composite material of claim 1, wherein said mixture further comprises a third component compatible with said salt and said hydrogen bond donating compound. The composite material according to claim 1 or 2, wherein the organic salt constituting the mixture is a compound represented by the following general formula (1) or (2).

(In the above general formulas (1) and (2), R ¹ ～R ⁸ are each independently an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, —(CH ₂ ) _m -OR ⁹ (R ⁹ is an alkyl group having 1 to 4 carbon atoms, and m is 1 to 4. ), a group represented by -(CH ₂ ) _n A group represented by —OH (n is an integer of 1 to 4), —(CH ₂ ) _p -OC(=O)R ¹⁰ (R ¹⁰ is an alkyl group having 1 to 4 carbon atoms, and p is 1 to 4. ) or -(CH ₂ ) _q -Y ¹ (Y ¹ is a halogen element, and q is 1-4. ) represents a group represented by X ^- is a monovalent anion. ) A composite material obtained by swelling a plurality of polymer chains fixed to a substrate with a mixture containing a salt and a hydrogen bond donating compound, the melting point of which is maintained at 100° C. or lower,
The salt is an inorganic salt that is solid at room temperature (25° C.),
the mixture has a melting point that is lower than the melting point of the salt that constitutes the mixture and the melting point of the hydrogen bond donor compound that constitutes the mixture;
A composite material further comprising a third component compatible with said salt and said hydrogen bond donating compound. The composite according to any one of claims 1 to 4 , wherein the mixture has a melting point maintained at 100 ° C. or less due to eutectic melting point depression caused by mixing the salt and the hydrogen bond donor compound. material. The composite material according to any one of claims 1 to 5 , wherein the mixture contains a hydrogen bond donating compound that is solid at room temperature (25°C). Any one of claims 1 to 6 , wherein the ratio of the salt and the hydrogen bond donating compound constituting the mixture is 1:0.5 to 1:12 in terms of the molar ratio of "salt:hydrogen bond donating compound". A composite material as described in . 8. The composite material according to any one of claims 1 to 7, wherein the plurality of polymer chains are covalently fixed on the substrate. 9. The composite material according to claim 8, wherein the plurality of polymer chains have a molecular weight distribution (Mw/Mn) of 1.5 or less. 10. The composite material according to claim 8, wherein the exclusive area ratio of the plurality of polymer chains to the surface area of the substrate is 10% or more. 11. The composite material according to any one of claims 8 to 10, wherein the layer containing the plurality of polymer chains and the mixture formed on the substrate has a thickness of 500 nm or more. The composite material according to any one of claims 1 to 11, wherein the plurality of polymer chains are polymer graft chains branched from a main polymer chain. The composite material according to any one of claims 1 to 12, wherein the plurality of polymer chains form a crosslinked structure.

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